This training program is entering its fifteenth year and has a full complement of 10 predoctoral trainees and four postdoctoral trainees. It achieved this size as the consequence of a merger between the current training grant in environmental carcinogenesis and mutagenesis and a separate NIEHS-funded training grant in toxicology. With the addition of appropriate new faculty, the number of preceptors is now 19. The majority of the toxicology training faculty are preceptors on this current program and have participated in mentoring predoctoral and postdoctoral trainees. The merger of the two programs has been seamless, and both trainees and preceptors have benefited from the broader scope of the program as a consequence of the inevitable cross fertilization. The major emphasis of the program remains the impact of environmental exposure on the genesis of disease, particularly cancers and also pulmonary dysfunction using molecular, genetic and toxicological approaches. The participating faculty are from four separate but interactive departments. They include the Department of Environmental Health, the Department of Cell Biology, Neurobiology and Anatomy, the Department of Molecular Genetics, Biochemistry and Microbiology, and the Department of Pediatrics, Institute for Developmental Research (IDR). Nationally, the Program fulfills an essential need to train individuals at the predoctoral and postdoctoral levels in the issues relating to biological, oncological toxicological consequences of environmental exposure. Institutionally, the Program has brought the research efforts of several laboratories into a common focus and facilitated collaborative efforts between these laboratories. Thus, the Program encourages the trainee to engage in research efforts that combine the expertise of several laboratories. This interdisciplinary approach provides the trainee with a broader-based background than is otherwise available. In the Institution, the Program has become recognized as key component in institutional efforts to support environmental health as one of its target focus areas, and the Program has been credited for spawning a much needed course in the "Biology of Cancer". Entering predoctoral trainees all have the equivalent of an undergraduate major in a chemical, biological or physical science with superior academic achievements. Postdoctoral candidates have proven academic accomplishments and hold the degrees of Ph.D., D.V.M. or M.D. Both predoctoral and postdoctoral trainees are selected from a national pool of applicants. The renewal application requests the number of predoctoral and postdoctoral trainees (10 and 4, respectively) currently supported by this training program remain the same for the next 5-year budget period. This programmatic size has proven optimal for the number of preceptors, the number of departments involved, and the extensive resources available to the trainees. It has fostered a collaborative environment between both trainees and their mentors.